A group of Spanish-speaking airplane cabin cleaners sued their employer Thursday alleging they were required to speak only English at work, which virtually silenced them on the job.

The lawsuit filed in Los Angeles Superior Court alleges that a shift manager started barring workers from speaking Spanish after Gate Gourmet took over the contract to clean Delta Air Lines planes at Los Angeles International Airport a year ago.

Most of the 14 workers speak little or no English, and many had been performing their jobs for years, said Victor Viramontes, national senior counsel at the Mexican American Legal Defense and Educational Fund, which is representing the plaintiffs.

"They're essentially muted," Viramontes said. "They've got to walk around with their mouth shut. So it is humiliating and denigrating, and it makes it harder for them to do their job."

Christina Ulosevich, a spokeswoman for Gate Gourmet, declined to comment on the specific allegations but said the company does not have an English-only rule.

The company trains and communicates "with our diverse workforce in multiple languages, and certainly in both English and Spanish in Los Angeles," she said in an email.

Under California law, employers can require workers to speak English if there is a business necessity.

According to the lawsuit, the workers are tasked with quickly cleaning cabins and restocking supplies before passengers board the plane, and they communicate over radio about when and where they need to go.

The company did not tell workers what consequences they would face for failing to heed the language rule, which appears to only affect those on the evening shift since morning and night crews continue to speak in Spanish, the lawsuit said.

Plaintiff Maria Martinez, 40, said she had been working nine years without a problem until Gate Gourmet issued the language rule. Now, she said she fears losing her job after getting a written warning for responding in Spanish to a question over the radio.

"How am I going to communicate in English if I don't know it?" Martinez asked.

The workers said they complained to human resources but got no response.

The lawsuit seeks to require Gate Gourmet to withdraw the language rule and pay damages and attorneys' fees.